Intelligence View
Critical 21Nails Exim bugs expose millions of servers to attacks
Newly discovered critical vulnerabilities in the Exim message transfer agent (MTA) software allow unauthenticated remote attackers to execute arbitrary code and gain root privilege on mail servers with default or common configurations. [.…
SOC Incident Playbook: Vulnerability Remediation & Verification
title: Detect Exploitation - Critical 21Nails Exim bugs expose millions of servers to attacks
id: a35cfbf0-a3c4-4b88-9924-429a9cb2e00e
status: experimental
description: Automatisch generierte SIEM-Erkennungsregel basierend auf CTI Intelligence
references:
- https://tsecurity.de/
author: iShareStuff CTI Automated Detection Engine
date: 2026-09-25
logsource:
category: network_connection
product: any
detection:
selection:
CommandLine|contains:
- 'exploit'
condition: selection
falsepositives:
- Legitime administrative Zugriffe oder Penetrationstests
level: high
tags:
- attack.initial_accessrule CTI_Threat_Indicator {
meta:
author = "iShareStuff CTI Automated Detection Engine"
date = "2026-09-25"
description = "YARA Signature for "
strings:
$str = "Critical 21Nails Exim bugs exp" ascii wide
condition:
any of them
}index=security sourcetype IN ("cisco:asa", "pan:traffic", "zeek_conn", "suricata", "WinEventLog:Security")
("Critical 21Nails Exim bugs expose millio")
| stats count earliest(_time) as first_seen latest(_time) as last_seen by src_ip, dest_ip, dest_host, signature
| eval first_seen=strftime(first_seen, "%Y-%m-%d %H:%M:%S"), last_seen=strftime(last_seen, "%Y-%m-%d %H:%M:%S")
| sort - countmessage: "*Critical 21Nails Exim bugs expose millio*"CommonSecurityLog
| where Message has "Critical 21Nails Exim bugs expose millio"
| summarize EventCount = count(), FirstSeen = min(TimeGenerated), LastSeen = max(TimeGenerated) by SourceIP, DestinationIP, DestinationPort, Activity
| extend DetectionRule = "iShareStuff-CTI-Compiled"
| sort by EventCount descMITRE ATT&CK Matrix Navigator 14 Taktiken
tsecurity.de Cognitive Threat RAG
Kognitive Analyse für identifizierte Bedrohung: Erhöhte Bedrohungslage im Bereich Critical 21Nails Exim bugs expose millio.... Basierend auf 368k Vektor-Korrelationen werden sofortige Isolationsmaßnahmen für betroffene Endpunkte empfohlen.
Netzwerk/Remote-Zugriff ohne Vorauthentifizierung möglich.
- 1. Perimeter-Inspektion: Relevante Portfreigaben und exponierte Endpunkte unverzüglich scannen.
- 2. Patch-Applikation: Hersteller-Hotfix einspielen oder betroffene Daemons in isolierte DMZ-Segmente überführen.
- 3. Telemetrie & EDR-Alerts: Prozessaufrufe und Child-Processes auf anomale Shell-Spawns überwachen.
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